Start with better brake pads, or upgrade to the Subaru 4 pug calipers. Putting $2,000 into the set-up of an Outback would not be cost affective there is to much to undo with the differences between an Outback and a normal Legacy or Legacy GT. Tires, yeah 60 series will help alot, better shocks maybe, hard to tell with the Outback. Consider saving for another car or Subaru that you can really mod for autocross or track time. Because of differences in the factory set-up for the Legacy Outback version most recommend not even starting the mod process.
My toy is an 83 Saab Turbo and it's taken me 3 years (and more than a couple of grand) to "get it ready", so don't rush it.
98 GT Wagon